Energizing circuit for a duplicating machine

ABSTRACT

Circuits for controlling the energization of a lamp and a heater in a copying machine include rectifiers for conducting respective half cycles of an AC power source to the lamp and the heater. Control is also provided for varying the instant which the heater and lamp are energized in each respective half cycle so as to vary the amount of current to each device. Additionally, the circuitry provides for pre-heating of the lamp and heater in order to preserve the life of the lamp and to reduce the time for the heater to attain its necessary temperature.

United States Patent Nakamura [54] ENERGIZING CIRCUIT FOR A DUPLICATING MACHINE [72] Inventor: Kitamaro Nakamura, Toyokawa,

Japan [73] Assignee: Minolta Camera Co., Ltd., Osakashi, Osaka-fu, Japan [22] Filed: Dec. 11, 1970 [21] Appl. No.: 97,120

[30] Foreign Application Priority Data Dec. 12, 1969 Japan ..44/99402 [52] US. Cl ..355/69 [51] Int. Cl. ..G03b 27/72 [58] Field of Search ..355/27, 64, 66, 100, 106, 67, 355/69 [56] References Cited UNITED STATES PATENTS 3,148,610 9/1964 Plante et al ..355/100 15] 3,692,408 51 Sept. 19, 1972 3,288,047 11/1964 Limberger ..355/100 Primary Examiner-Samuel S. Matthews Assistant Examiner-Michael L. Gellner AttorneyWatson, Cole, Grindle & Watson [57] ABSTRACT 4 Claims, 13 Drawing Figures PATENTEDSEPIQ m2 3.692.408

SHEET 2 [1F 4 H6140 FIG. 40 M40 PATENTED 1 9 I97? 3. 692,408

SHEET 3 or 4 INVENATOR.

ENERGIZING CIRCUIT FOR A DUPLICATING MACHINE BACKGROUND OF THE INVENTION The present invention relates to a circuit for energizing a lamp and a heater in a copying machine and more particularly'a circuit for energizing the lamp and the heater alternately on different half cycles of the AC power source.

In general, a copying machine is provided with a light source for exposure of the original, a heater for drying and fixing the copy, and a motor driving source, and in addition a circuit for controlling the machine. The major part of the power for the copying machine is consumed by the heater and the lamp. And, in a copying machine using an incandescent lamp or a halogen lamp as a light source, in order to prevent fogging, to save power, to prolong the life of the lamp, and to prevent an unnecessary temperature rise due to lighting the lamp, the lamp is lit only at the time of exposure. Also the heater is always energized in order to keep it ready and at the time of exposure the consumption power of the lamp and the consumption power of the heater and the other circuits are added together to form the peak consumption power. I

And, in proportion to the speed of a copying machine, the consumption power of the lamp and the heater has a tendency to remarkably increase. Further, in the case wherein a commercial power source is put to use the peak consumption current of the copying machine approaches the limit of the current output thereof, thereby preventing further speeding up of the copying machine.

As a means of overcoming this problem, by short-circuiting the heater at the time of lighting the lamp and by feeding the heater only at the time of putting out the lamp the peak value of the consumption current can be lowered, and in the case wherein a commercial power source is put to use, with regard to the current rating for the indoor wiring, cords, plug sockets, and the like it is possible to increase the wattage for the lamp and the heater.

In that case, however, there is another consideration, that is, it is impossible to simultaneously light the lamp and the heater and effect the next exposure while drying and fixing a copy, and accordingly the efficiency of the copying machine is reduced. In addition, the heater becomes cool meanwhile, and it takes a considerable time for that heater to get to the proper heating state, so that it is difficult to get a good timing for when the exposed and developed photo-sensitive paper passes through the drying and fixing section and the time when the heater is fed.

OBJECT OF THE INVENTION One object of the present invention is to provide an energizing circuit for a lamp and a heater in a copying machine, which in order to remove the prior drawbacks mentioned above effects a very short intermittent feed at the different half cycles of the AC power source to the lamp and the heater and prevents the peak value of the consumption current from running to excess while lighting simultaneously the lamp and heater.

Another object of the present invention is to provide an energizing circuit for a lamp and a heater in a copying machine, which controls the current to the lamp and the heater at different half cycles of the AC power source by means of a silicon control rectifier such as Thyristor or Triac, and facilitates the variation adjustment of current by altering the current phase angle.

Further another object of the present invention is to provide an energizing circuit for a lamp and a heater in a copying machine, which controls the current phase angle to the lamp and the heater at different half cycles of the AC power source by means of a silicon control rectifier, and lights the lamp and preheats the heater at the time of exposure, and when the exposure is not operative preheats the heater so as to facilitate the shift of the heater to a constant heating state, and at the same time preheats the lamp to prevent the filament from breaking and prolongs the life of lamp especially in the case of where a halogen lamp is put to use as a light source lamp.

The other objects of the present invention will be apparent from the description of the embodiments disclosed hereinafter.

SUMMARY OF THE INVENTION In order to attain the above-mentioned objects the present invention provides an energizing circuit for a lamp and a heater in a copying machine, which connects the lamp and the heater to an AC power source having a voltage higher than the rated voltage of the lamp and heater, and controls the current from the power source respectively to the lamp and the heater by means of a silicon control rectifier. The silicon control rectifier controls the phase of the AC power source for feeding the rated current or a larger current to the lamp and the heater so as to be respectively of a different phase.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I shows an energizing circuit of an embodiment in accordance with the present invention.

FIG. 2a and 2b show the wave forms of the voltage in that embodiment, wherein FIG. 2a shows the wave form of the voltage impressed on the lamp and FIG. 2b shows the wave form of the voltage impressed on the heater.

FIG. 3 shows an energizing circuit of another embodiment in accordance with the present invention.

FIGS. 4a, 4b, and 40 show the wave forms of the voltages impressed on the lamp and the heater in the embodiment of FIG. 3, wherein FIGS. 4a, 4b and 40 show respectively the wave form of the voltages and the respective variation of the conduction angle.

FIG. 5 shows an energizing circuit of a third embodiment in accordance with the present invention.

FIG. 6 shows an energizing circuit of a fourth embodiment in accordance with the present invention.

FIGS. 7a and 7b show wave forms of the voltage at the time when the lamp filament is preheated and the heater is heated in the embodiment of FIG. 6, wherein FIG. 7a shows the wave form of the voltage impressed on the lamp and FIG. 7b shows the wave form of the voltage impressed on the heater.

FIGS. 8a and 8b show wave forms of the voltage at the time when the lamp is fully lit and the heater is preheated in the embodiment of FIG. 6, wherein FIG. 8a shows the wave form of the voltage impressed on the lamp and FIG. 8b shows the wave form of the voltage impressed on the heater.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows the first embodiment in accordance with the present invention, wherein to power source 1 lamp 3 and heater 4 are connected in series through power switch 2. The voltage of power source 1 is higher than the rated voltages E,, E of lamp 3 and heater 4.

To lamp 3 Thyristor 5, is connected in parallel for short-circuiting lamp 3, and to heater 4 Thyristor 5 is connected in series in the reverse direction of Thyristor 5, for short-circuiting heater 4. And, to Thyristors 5,, 5 RC circuits are provided in parallel for controlling the conduction and non-conduction of both Thyristors. That is, to Thyristor 5 a circuit composed of resistance 8, and condenser 9, is connected in parallel and to Thyristor 5 a circuit composed of resistance 8 and condenser 9 is connected in parallel. RC nodes m, n of both RC circuits are respectively connected to changeover contacts 7a, 7b of change-over switch 7, and change-over switch 7 is connected to change-over switch 6. One change-over contact 6a of change-over switch 6 is connected to the gate of Thyristor 5, and the other change-over contact 6b is connected to the gate of Thyristor 5 and both change-over switches are arranged so that when change-over switch 7 is connected to the change-over contact 7a side by means of connection member 10 change-over switch 6 is connected to change-over contact 6a, and when change-over switch 7 is connected to the change-over contact 7b side change-over switch 6 is change-over to contact 6b.

Now, when change-over switch 7 is not connected to change-over contact 7a nor 7b, both Thyristors 5,, 5, become non-conductive, and in lamp 3 and heater 4 the voltages of power source 1 are impressed. In this case, provided both the heater and lamp are equal:

then, as shown by d in FIGS. 2a, b, the voltage E /2 is impressed on lamp 3 and heater 4 and that voltage is considerably lower than the rated voltages of lamp 3 and heater 4, so that both are only preheated.

Next, when change-over switch 7 is connected to the contact 70, change-over switch 6 is connected to contact 6a by connection member 10 and the voltage of node in is impressed on the gate of Thyristor 5,, and when the m side of condenser 9, is charged, Thyristor 5, is activated, and when the in side of condenser 9, is charged on the reverse half cycle Thyristor 5, becomes non-conductive. When Thyristor 5, is activated lamp 3 is short-circuited and on heater 4 the power source voltage E is impressed, and when Thyristor is nonconductive, lamp 3 and heater 4 connected in series to each other the power source voltage is impressed and accordingly lamp 3 is preheated by the voltage shown by g in FIG. 2a and heater 4 is heated by the voltage shown by g in FIG. 2b.

And, when change-over switch 7 is connected to contact 7b, on the gate of Thyristor 5 the voltage of node n is impressed and when the n side of condenser 9 is at a positive potential Thyristor 5 is activated and the heater is short-circuited. When Thyristor 5 becomes non-conductive and the power source voltage is impressed on lamp 3 and heater 4 connected in series to each other, and the voltage shown by f in FIGS. 2a, b is fed respectively to lamp 3 and heater 4 to fully light lamp 3 and preheat heater 4.

Provided the rated voltage of lamp 3 is E, and the effective value voltage to be impressed is E,,, it is known that light output from the lamp increases in proportion to (E /E,)" from (E /E0 If for example, E, l 10 V, the AC power source and voltage to be applied are 220 V, and if the half-wave voltage is applied to lamp 3, the effective voltage E is 157 V. Results of experiments show that the brightness of the lamp is l 57/ l l0) 4L where X 4. When the effective voltage of the wave form shown by f in FIG. 2a is higher than the rated voltage of lamp 3 the quantity of light emitted from the lamp can be remarkably increased. in this case, the voltage over the rated voltage of the lamp is impressed on the lamp, however, that voltage is impressed at the half-wave phase of the power source voltage instantaneously, so that the lamp filament is not damaged. As the quantity of light emitted from the lamp is increased while the continuous lighting time of the lamp is shortened, therefore, the possible copying number in the duration of the life time of the lamp is not substantially decreased.

As described above, on lamp 3 and heater 4 the voltage to always preheat them is impressed, so that in the case of heater 4 the heating time is speedy, and when a halogen lamp is put to use and the durability of the lamp filament can be increased.

In the first embodiment described above, when the lamp and the heater are required to be energized simultaneously change-over switch 7 is changed over to the contact 7a and the contact 7b in accordance with the power source frequency, however, even in such a case no excess current is required as a whole from the copying machine.

in the second embodiment shown in FIG. 3 in accordance with the present invention, the voltage of power source 1 is boosted to about twice the voltage of the lamp and the heater to be used, by means of transformer l1, and to the secondary circuit of transformer 11 a series circuit of lamp 3 and Thyristor 5,, and a series circuit of heater 4 and Thyristor 5 are connected in parallel, and both Thyristors 5,, 5 are inserted so as to conduct in the reverse direction.

To Thyristor 5, a phase control circuit composed of variable resistance 8, and condenser 9, is connected in parallel, and RC node in is connected to the gate of Thyristor 5, through switch 12, and in the same way RC node n of another phase control circuit composed of variable resistance 8 and condenser 9 connected in parallel with Thyristor 5 is connected to the gate of Thyristor 5 through switch 12 Therefore, lamp 3 and heater 4 are energized by the half-wave having respectively one half cycle phase difference of AC power source 1 as shown-in FIG. 4, and that energization is phase-controlled by the control circuit. Therefore, by controlling properly variable resistances 8,, 8 the conduction phase angle can be varied as shown in FIG. 4a, b and 0. FIG. 4a shows the state wherein the lamp and the heater are given about one-fourth phase angle conduction, and the effective voltage is remarkably dropped, and thereby the lamp and the heater are preheated. FIG. 4b shows the state wherein the lamp and heater are fed with an excess voltage, and FIG. 40 shows the state wherein the lamp is fed weakly and the heater is fed with an excess voltage.

In the case of FIG. 4b, provided the secondary voltage of transformer 11 is as high as twice the rated voltage E of the lamp and the heater, AC half-waves of the voltage of 215,, are fed, and provided resistance of lamp 3 and heater 4 are respectively R,, R the consumption power P of lamp 3 and the consumption power P,,' of heater 4 are as follows:

These formulas show that both consumption powers become larger than consumption powers P P at the time when the lamp and the heater are respectively lit with the rated voltage, but as with resistance values R,, R in this case resistances R,,R become higher, so that as compared with the case of that in which the lamp and the heater are lit simultaneously with the rated voltage, the consumption power is decreased as follows:

On the other hand, as described above the brightness progresses from (E/E to (E/E,,( so that very large quantities of light and heat can be obtained and as a result of experiments the quantity of light could be increased from 4 to 5 times and the heat could be increased to 2 times the original amount.

Besides, ,in the second embodiment the phase adjustment can be done by variable resistances 8,, 8 so that the temperature rise of the heater at the beginning of use can be speeded up and the drying efficiency can be adjusted in relation to the ambient temperature.

In the third embodiment shown in FIG. 5 in accordance with the present invention, the voltage of power source 1 is boosted by transformer 11 and in the secondary circuit of transformer 11 Triac 14 is inserted, and to Triac 14 a circuit composed of switch 13,, lamp 3, and rectifier 5,, and a circuit composed of switch 13 heater 4, and rectifier 5 are connected in parallel with each other, and rectifiers 5, and 5 are connected in reverse directions of conduction, and Triac 14 can be controlled by trigger transformer 15.

Further, instead of rectifiers 5,, 5 a phase control circuit can be used as shown in the second embodiment described above.

If switches 13, and 13 are closed and turned on, current is fed into heater 4 by rectifiers 5, and 5 in the course of the positive half wave of the power source and also into lamp 3 in the course of the negative half wave. If switch 13 is opened and switch 13, is closed, the lamp only can be lighted by the half wave. If switch 13, is opened and switch 13 is closed, heater 4 can be heated by the half wave. The lighting voltage wave form is as shown in FIG. 4b.

In the fourth embodiment shown in FIG. 6 in accordance with the present invention, lamp 3 and Triac 14, are connected in parallel, and heater 4 and Triac 14 are connected in parallel, and both are connected in series to power source 1 and power switch 2. And, Triac 14, is provided with a trigger circuit composed of resistance 8, and condenser 9, and Triac 14 is provided with another trigger circuit composed of variable resistance 8 and condenser 9 and capable of Changing the trigger time, and from the node of both parallel elements both trigger circuits are changed over to connect by switch 16 through contacts 16a, 16b.

Both Triacs 14,, 14 are energized by the discharge of condenser 9, or 9 in an appropriate trigger circuit when switch 16 is connected to contact 16a or 16b in the trigger circuit. The trigger circuit for Triac 14 can change the discharge time of condenser 9 by adjusting variable resistance 8 For switch 16 a timing switch is put to use, for example, when the power switch is closed, switch 16 is connected to contact 16a and when the original copy is delivered to the exposure portion switch 16 is changed over to contact 16b, and after the original copy is irradiated for a certain time switch 16 is returned again to contact 16a.

And thus, right after the power switch is closed, Triac 14 for which switch 16 is opened is non-conductive as well as Triac 14, for which switch 16 is closed, so that lamp 3 and heater 4 are preheated with a low voltage for the time shown by t, in FIGS. 7a, b. After time t, elapses condenser 9, discharges and Triac 14, is energized because its gate is turned ON, and lamp 3 is short-circuited and the whole power voltage is impressed on heater 4 and accordingly heater 4 is heated. However, when the half-cycle of the power wave form changes Triac 14, becomes non-conductive again, and lamp 3 and heater 4 are preheated with a low voltage. After time t, elapses again and when condenser 9, is discharged lamp 3 is short-circuited and the whole voltage is impressed on heater 4, and lamp 3 is preheated with the voltage shown in FIG. 7a and heater 4 is heated with the voltage shown in FIG. 712.

Next, when switch 16 is changed over to the contact 16b on account of the delivery of the original copy as described hereinbefore, Triac 14, holds always a nonconductive state and Triac 14 is energized whenever condenser 9 is discharged after time t, elapses. These operations are repeated each half-wave of the power wave form so that lamp 3 is lit with the voltage shown in FIG. 8a and heater 4 is energized to preheat with the low voltage shown in FIG. 8b. When the resistance value of variable resistance 8 is changed discharge time t of condenser 9 is changed and the effective value of the voltage impressed in lamp 3 is changed and accordingly the brightness of lamp 3 can be changed.

Then, after a certain time elapses timing switch 16 is changed over again to the contact 16a.

As is clear from the above description of the embodiments in the present invention the lamp and the heater are simultaneously fed so as to prevent the peak consumption current and the lamp and the heater are always preheated, so that there is no breaking of filaments due to an abrupt feed. And when a halogen lamp is put to use the lamp holds the halogen cycle by means of the remaining heat to prolong the life of the lamp and the constant pre-heating state of the heater can be rapidly effected.

From the description disclosed above, the operation of the energizing circuits in accordance with the present invention is believed to be apparent.

I claim: 1. A circuit for energizing at least one lamp and at least one heater from an AC power source in a copying machine, comprising:

first and second unidirectional conductive switch means connected to conduct current from respective half cycles from said AC power source, said first unidirectional conductive means connecting said AC power source with said at least one lamp and said second unidirectional conductive means connecting said AC power source to said at least one heater; means for controlling the excitation of said first and second unidirectional conductive means; and

means for switching said first and second unidirectional conductive means to be activated by said means for controlling.

2. A circuit as in claim 1 wherein said means for switching may be positioned to independently energize said at least one heater or said at least one lamp, said means for switching is positioned to simultaneously fully energize said at least one lamp and said at least one heater, and said means for switching further includes means for varying the instant of energization of said at least one lamp and said at least one heater during a respective half cycle of said AC power source.

3. A circuit as in claim 1 wherein said first and second unidirectional conductive switch means are serially connected across said AC power source; said at least one heater and said at least one lamp are serially connected across said AC power source, and said means for switching comprises first and second ganged two-position switches wherein a first position actuates said first unidirectional conductive switch means and a second position actuates said second unidirectional conductive switch means.

4. A circuit as in claim 2 wherein said first unidirectional conductive switch means is serially connected with said at least one lamp across said AC power source, said second unidirectional conductive switch means is serially connected with said at least one heater across said AC power source, said switch means comprises first and second switches for respectively energizing said first and second unidirectional conductive switch means and said means for varying the instant of actuation of said first and second unidirectional conductive switch means comprises first and second variable resistors respectively connected to said first and second switches.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,692,408 Dated September 19, 1972 Inventor(s) K113 amaro mura It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

[ 73] Assig'nee: Minolta Camera Kabushiki Kaisha,

} Osaka-shi, Osaka-fu, Japan Signed and sealed this 22nd day of May 1973.

(SEAL) Attest:

EDWARD .M.FLETCHER,JR. I 7 ROBERT GOTTSCHALK- Attesting Officer Commissioner of Patents ORM PO-1050 (10-69) USCOMM-DC 60376-P69 UIS. GOVERNMENT PRINTING OFFICE: 19! O-36G'334,

UNITED STATES PATENT oTTTcE QERHFICATE @IF RRETIN Patent 3,692,408 Dated September 19, 1972 lnventofls) Kitamaro Nakamura It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:

[ 73] Assignee: Minolta Camera Kabushiki Kaisha,

Osaka-shi, Osaka-fu, Japan Signed and sealed this 22nd day of May 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. I ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents DRM F'O-IOSO (10-69) USCOMM-DC 60376-P69 u.s. GOVERNMENT PRINTING OFFICE 1959 o-ass-au, 

1. A circuit for energizing at least one lamp and at least one heater from an AC power source in a copying machine, comprising: first and second unidirectional conductive switch means connected to conduct current from respective half cycles from said AC power source, said first unidirectional conductive means connecting said AC power source with said at least one lamp and said second unidirectional conductive means connecting said AC power source to said at least one heater; means for controlling the excitation of said first and second unidirectional conductive means; and means for switching said first and second unidirectional conductive means to be activated by said means for controlling.
 2. A circuit as in claim 1 wherein said means for switching may be positioned to independently energize said at least one heater or said at least one lamp, said means for switching is positioned to simultaneously fully energize said at least one lamp and said at least one heater, and said means for switching further includes means for varying the instant of energization of said at least one lamp and said at least one heater during a respective half cycle of said AC power source.
 3. A circuit as in claim 1 wherein said first and second unidirectional conductive switch means are serially connected across said AC power source; said at least one heater and said at least one lamp are serially connected across said AC power source, and said means for switching comprises first and second ganged two-position switches wherein a first position actuates said first unidirectional conductive switch means and a second position actuates said second unidirectional conductive switch means.
 4. A circuit as in claim 2 wherein said first unidirectional conductive switch means is serially connected with said at least one lamp across said AC power source, said second unidirectional conductive switch means is serially connected with said at least one heater across said AC power source, said switch means comprises first and second switches for respectively energizing said first and second unidirectional conductive switch means and said means for varying the instant of actuation of said first and second unidirectional conductive switch means comprises first and second variable resistors respectively connected to said first and second switches. 